-----------------------------------

SapphireBlue

Tue May 03, 2011 8:54 pm


Calculator

-----------------------------------

Hello,

I am a beginner in the program Eclipse. I have to do an assignment that is due tommorrow on a Calculator program that can just add numbers. I am having trouble when I press a number adding another number and then pressing an equal sign, the answer is not given. Here is my code so far:

/*
 * Created on Apr 29, 2011
 *
 * TODO To change the template for this generated file go to
 * Window - Preferences - Java - Code Style - Code Templates
 */

/**
 * @author 301687257
 *
 * TODO To change the template for this generated type comment go to
 * Window - Preferences - Java - Code Style - Code Templates
 */

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Calculator extends JFrame implements ActionListener {
 JTextField text = new JTextField (20);
 Button b, b2, b3, b4, b5, b6, b7, b8, b9, c, c2, c3, c4;
 
 private int numClicks = 0; 
 int num, num1, num2, num3 = 2; 
 int counter = 0;
 String numbers = ""; 
 String sum = "";
 double temp = 0;
 double mainNum; 
 
 //Constructor
 public Calculator (String Title){
  super (Title);
  setSize(200, 300);
  setLayout (new FlowLayout ());
  b = new Button("Clear");
  add (b);
  add (text);
  b.addActionListener(this);
  b2 = new Button("1");
  add (b2);
  add (text); 
  b2.addActionListener(this);
  b3 = new Button ("2");
  add (b3);
  add (text); 
  b3.addActionListener(this);
  b4 = new Button ("3");
  add (b4);
  add (text);
  b4.addActionListener(this);
  b5 = new Button ("4");
  add (b5);
  add (text);
  b5.addActionListener(this);
  b6 = new Button ("5");
  add (b6);
  add (text);
  b6.addActionListener(this);
  b7 = new Button ("6");
  add (b7);
  add (text);
  b7.addActionListener(this);
  b8 = new Button ("7");
  add (b8);
  add (text);
  b8.addActionListener(this);
  b9 = new Button ("8");
  add (b9);
  add (text);
  b9.addActionListener(this);
  c = new Button ("9");
  add (c);
  add (text);
  c.addActionListener(this);
  c2 = new Button ("0");
  add (c2);
  add (text);
  c2.addActionListener(this);
  c3 = new Button ("+");
  add (c3);
  add (text);
  c3.addActionListener(this);
  c4 = new Button ("=");
  add (c4);
  add (text);
  c4.addActionListener(this);
  
 }
 
 
 /* (non-Javadoc)
  * @see java.awt.event.ActionListener#actionPerformed(java.awt.event.ActionEvent)
  */
 public void actionPerformed(ActionEvent e) {
  // TODO Auto-generated method stub
  //   TODO Auto-generated method stub
   
  
  if (counter == 0)
   num1 = num;
   counter++; 
  if (counter == 1)
   num2 = num1;
   counter++; 
  
  if (e.getSource()==b)
  	text.setText("0.");
  else if (e.getSource()==b2)
   //System.out.println ("1");
   text.setText("1");
  else if (e.getSource()==b3)
   text.setText("2");
  else if (e.getSource()==b4)
   text.setText("3");
  else if (e.getSource()==b5)
   text.setText("4");
  else if (e.getSource()==b6)
   text.setText("5");
  else if (e.getSource()==b7)
   text.setText("6");
  else if (e.getSource()==b8)
   text.setText("7");
  else if (e.getSource()==b9)
   text.setText("8");
  else if (e.getSource()==c)
   text.setText("9");
  else if (e.getSource()==c2)
   text.setText("0");
  else if (e.getSource()==c3)
   text.setText("+");
  else if (e.getSource () == c4)
   
  numbers = ""; 
  
  //text.setText(sum);
  counter++;
  //System.out.println (num); 
  num1 = num;
  num2 = num3; 
  
 }
 
 public static void main(String[] args) {
  Calculator myWindow = new Calculator("Calculator");
  myWindow.setVisible(true);
 }
}

For a better version, please see the attachment. Feel free to make any changes to it as much as possible. Thanks.


-----------------------------------

deltamanx

Thu May 05, 2011 3:20 pm


Re: Calculator

-----------------------------------

Here's your problem:
[code]
  if (counter == 0)
    num1 = num;
    counter++;
  if (counter == 1)
    num2 = num1;
    counter++;[/code]

The problem is, in Java, when you have an if structures that
has more than one line of code, you need brackets as follows:
[code]
  if (counter == 0)
  {
    num1 = num;
    counter++; 
  }
  if (counter == 1)
  {
    num2 = num1;
    counter++; 
  }[/code]

Hope this helps!